THE BLOG
10/23/2008 05:12 am ET Updated Nov 17, 2011

7 Brain Teasers to Ace Job Interviews

A recent CNN article explains well why a growing number of companies use brainteasers and logic puzzles of a type called "guesstimations" during job interviews:

"Seemingly random questions like these have become commonplace in Silicon Valley and other tech outposts, where companies aren't as interested in the correct answer to a tough question as they are in how a prospective employee might try to solve it. Since businesses today have to be able to react quickly to shifting market dynamics, they want more than engineers with high IQs and good college transcripts. They want people who can think on their feet."

What are technology companies (Google, Microsoft, Amazon) and consulting companies (McKinsey, Boston Consulting Group, Accenture...) looking for? They want employees with good so-called Executive Functions: problem-solving, cognitive flexibility, planning, working memory, decision-making, even emotional self-regulation (don't try to solve one of these puzzles while being angry, or stressed out).

Want to try a few? Below you have our Top 7 Guesstimations/ Logic Puzzles for Job Interviews and Brain Challenge:

Please try to GUESS the answers to the questions below based on your own logical approach. The goal is not to find out (or Google) the right answer, but to 1) identify the logic approach that will help "guesstimate" an appropriate range, say + or - 50% of the actual answer, and then 2) complete the calculations (ideally mentally, but you can also take notes) to provide an estimate.

1) How many times heavier than a mouse is an elephant?.

2) How many firefighters are there in San Francisco?.

3) How many trees are there in NYC's Central Park?.

5) How many golf balls can fit in a school bus?.

6) In 1999, how were these baby boy names ranked by popularity: Kevin, Jose, Hugh.

7) What is the weight of a large commercial airplane?.

The Answer appear below. Again, the key here is to try, plan the steps towards the solution, and do the mental calculations to find a reasonable range. That's the brain challenge. The goal is not to find the precise correct answer.

1) Around 150,000. An average elephant weighs 4,000 kg on average; an average mouse 25 grams.

2) Around 350 firefighters on duty on any given day, out of a pool of 1700 firefighting overall staff.

3) There are over 26,000 trees (of approximately 175 species) in the Park.

4) We don't know (or need to know) how many pairs you have had.

5) About 500,000, assuming the bus is 50 balls high, 50 balls wide, and 200 balls long.

6) Rankings of baby boy names in 1999, according to Social Security Administration: 1. Jose (#30), 2. Kevin (#32), 3. Hugh (#830).

7) For a Boeing 747:
- Empty: around 400,000 pounds (lbs), or 181 metric tons
- Maximum Takeoff Weight: around 825,000 pounds, or 374 metric tons
- For context, the weight of an empty Hummer is 8,600 pounds.

Some Context on Executive Functions:

If you want to learn more about what they are, here are some quotes from my Interview with neuropsychologist Dr. Elkhonon Goldberg on cognitive fitness:

Alvaro Fernandez: "Please tell us more about what the Frontal Lobes are."

Elkhonon Goldberg: "We researchers typically call them the Executive Brain. The prefrontal cortex is young by evolutionary terms, and is the brain area critical to adapt to new situations, plan for the future, and self-regulate our actions in order to achieve long-term objectives. We could say that that part of the brain, right behind our forehead, acts as the conductor of an orchestra, directing and integrating the work of other parts of the brain".

"I provide a good example in The Executive Brain book, where I explain how I was able to organize my escape from Russia into the US. Significantly, the pathways that connect the frontal lobes with the rest of the brain are slow to mature, reaching full operational state between ages 18 and 30, or maybe even later. And, given that they are not as hard-wired as other parts of the brain, they are typically the first areas to decline".

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Ready for that job interview now (on either end of the table)? In case they help, here you have more brain teasers.

Note: I have made a couple of corrections based on a comment below. Thank you, Ben!

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